1. Technical Field
The present invention relates to a multi-mode communication system and a method thereof. More particularly, the present invention relates to a multi-mode communication system that can efficiently perform various types of wireless access.
2. Background Art
Power consumption is an issue for various wireless communication devices such as a conventional mobile communication terminal, a portable Internet terminal, a wireless personal area network (WPAN), or a sensor network node. Accordingly, the communication devices stay in an idle state when they are not in a communication state such that they can maintain a standby state while using a minimum amount of power when no data is communicated. This can be represented as sleep and awake, in which user equipment sleeps during the idle state while using the minimum amount of power and periodically wakes up for receiving and processing broadcasting information or paging information from a system. Therefore, the communication apparatus stays in the idle state after being applied with power and participates in minimal operation until receiving a user's request, and periodically wakes up at a predetermined time slot for receiving broadcasting information from a base station or a coordinator (i.e., an access point) and updating relevant information, and responds to the user's request.
The communication apparatus receives paging information from a base station or the coordinator at the corresponding time slot, compares a received ID and its own ID, and performs a paging response process when the two IDs are identical. In addition, the communication apparatus registers a new location with the coordinator when a location of the UE is changed as it moves to another location. However, a periodic pooling of the UE in the idle state causes power consumption of the communication apparatus due to state transition and data transmitting/receiving, and accordingly, an operation time of the UE is significantly reduced.
As described, when UE in which various wireless access techniques are integrated is used, that is, when multi-mode UE is used, the multi-mode UE must be periodically operated in accordance with respective idle states of all radio access systems that the multi-mode UE can access. Therefore, power of the multi-mode UE is more quickly exhausted since each radio access system has a different sleep/awake time. In the worst scenario, the multi-mode UE must be awake all the time, and accordingly, the purpose of the idle state becomes redundant.
FIG. 1 is a block diagram of a conventional multi-mode wireless communication system that provides various wireless access modes.
As shown in FIG. 1, a conventional multi-mode wireless communication system includes user equipment (UE) 10, a first radio access system (AS) 20, a second radio AS 30, a third radio AS 40, a first mobility control entity (MCE) 50, a second MCE 60, and a third MCE 70. The UE 10 includes a plurality of communication protocols and provides multi-mode communication, the first, second, and third radio ASs 20, 30, and 40 respectively perform wireless access in accordance with multi-mode selection of the UE 10, and the first, second, and third MCEs 50, 60, and 70 respectively perform mobility management of the UE 10, user authorization, and access control.
As shown in FIG. 1, the conventional multi-mode wireless communication system repeats a sleep/awake operation 7 according to communication periods (operation periods and paging periods) 21, 22, and 23 of the first, second, and third ASs 20, 30, and 40, and in the worst case, the conventional multi-mode wireless communication system stays in the awake state waiting for a process corresponding to a received message broadcasted through each radio access and a paging request, and therefore, advantages of the idle state cannot be realized and power is unnecessarily wasted.
Until now, no paging process has been provided for multi-mode UE, nor has a method for transmitting a paging message in a dual mode environment in which a radio access system such as a global system for mobile communication (GSM) system or a wireless code division multiplexing access (WCDMA) system uses the same mobile switching center (MSC) been suggested.
In the GSM system and the WCDMA system, a paging message is transmitted to an MSC that is commonly used for respective radio access systems, and the MSC adds information on a specific system that processes the paging message to the paging message and transmits the paging message to the respective radio access systems. The specific system may include a GSM system or a WCDMA system. When receiving the paging message from a radio access system that has been waiting to receive data or is currently being used, the multi-mode UE determines whether to respond to the paging message. When it is determined to respond to the paging message, the multi-mode UE transmits a paging response to a radio access system through which the GSM system or the WCDMA system requests and receives application services. However, this method has the following problems.
1. It is available only for the same type of systems (e.g., GSM system and WCDMA system) that can share an MSC.
2. It does not suggest a method for using various services by simultaneously using various radio access systems. (When a current service provided to an access system can be provided to a specific access system having received a paging message, a handover is performed from the current access system to the specific access system and thus both of the existing service and a paged service can be provided. Otherwise, the paging request is refused and only the existing service is served.)
3. There is no way of applying various Internet Protocol (IP)-based packet application policies since a paging control system located in the MSC only checks whether a service can be provided.
4. The MSC does not know which radio access system that the multi-mode UE in the idle state is waiting for, and thus the paging message must be transmitted to all the radio access systems involved with the multi-mode UE.
5. Since it is not informed which radio access system the multi-mode UE should access, power consumption of the multi-mode in the idle state cannot be efficiently managed.
Conventionally, there has been provided a method for processing a paging operation of multi-mode UE through a shared data transmission device (e.g., an MSC) in a mobile communication network, wherein the data transmission device can be shared within a core network. However, this method cannot be applied to a radio access system (e.g., a wireless local area network (WLAN) or a wireless wideband (WiBRO)) that cannot share the data transmission system, and information on currently waiting radio access systems cannot be provided.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.